His last book changed how we see history. This one destroys your future.

In the future, will humans become immortal, yet anxious, gods? Or will they become soulless devotees of data who worship at the altar of algorithms?

That's the choice posed by Homo Deus: A Brief History of Tomorrow, historian Yuval Harari's long-awaited follow-up to Sapiens: A Brief History of Humankind. (Longer awaited in the U.S., where Homo Deus finally arrived this week. It was published in Europe last year.)

If you haven't read Sapiens, get it on your bedside table immediately. It's one of those books, like Jared Diamond's Guns, Germs and Steel and Howard Zinn's A People's History of the United States, that is powerful enough to change your entire worldview even if you're not the sort of person who reads nonfiction.

Harari is an Israeli professor who set out to write a book for his students that would give them a grounding in human history as a whole. It has since been translated into 30 languages, recommended by Bill Gates and Mark Zuckerberg, and made Harari a fixture on the TED speaker circuit. It's fair to say he overshot his goal.

The elevator pitch version of Sapiens

The thing that sets humans apart from the rest of nature isn't technology. Turns out animals are pretty good at toolmaking. Everything we have made of our world rests on our ability to cooperate on a global level — by sharing a powerful layer of fictional reality.

Money, countries, trade, religion, law, human rights, standards of beauty: people invented all these things in their minds, then we agreed to believe in them. When enough of us stop believing, they change or vanish.

Sapiens preceded the 45th President, but in this light he's nothing new. By insisting on "alternative facts" and trying to make us believe him, he and his troops are exhibiting an age-old human tendency. He's waging war on the only battlefield that matters.

Homo Deus: A Brief History of Tomorrow

Now with Homo Deus, Harari tries to take his insights into the stories we tell ourselves and spin them forward. He thinks we've got the 21st century all wrong.

It's not an age of war and terrorism and international spy drama; all of the above are winding down in the long run, no matter who gets elected in the short term.

Instead, as befits social media-obsessive human beings, we're making this era all about us. Our main battles aren't nation-state wars. They are about that which makes us happy in every conceivable way — because the story we're telling ourselves all the time now is that we have the right to be happy.

Of course, the world's biggest impediment to happiness is death. But with the march of medical progress, we feel — not unreasonably — that we can live longer and longer with each generation. "All wars are nothing compared to the battle for eternal youth," Harari says of this War on Death, which he calls the "flagship project" of our century.

High expectations in the pursuit of happiness

He also cautions that if it succeeds — say, the average age of death at the end of the century is 150 — we may actually end up less happy than ever. Our expectations for what we should do with all that time will be sky high. And if accidents were the only real way you could die before that age, you'd be hit with anxiety attacks every time you left your apartment.

So the second great battle for happiness is to change our biochemistry; to force ourselves to feel as good and outgoing and productive as possible, constantly, no matter our external stimuli. Thanks to Zoloft, Prozac, Wellbutrin and all the gang, we're well on our way. The next big wellness craze might be "transcranial stimulators" — brain-jolting helmets that give us the burning desire to, say, practice piano all the time.

And while we're messing around with our heads, we might as well upgrade ourselves into supreme beings. Bionic hands, artificial eyes, nanobots in the bloodstream: Pretty soon we'll reach a point where we're no longer Homo Sapiens (literally, man the wise) and have become Homo Deus: man the god.

Two ways out of this disturbing future

We could become part of a massive new underclass of "useless bums" with drugs and video games.

Is there any way out from this disturbing future of self-driven, high-functioning immortal automatons? Harari offers us two.

First of all, we could become part of a massive new underclass of "useless bums" — he means that in the best possible way — sating ourselves with drugs and video games, unable to find jobs in the robot-driven economy but subsisting on universal basic income.

Harai described this aimless life as "la la land," apparently unaware that would sound pretty good after the next Oscars.

Secondly, we could join the new religion of "Dataism," which basically sounds like one massive global Google running everything. Under the rule of dataism, politicians will be entirely irrelevant. The algorithm rules. Strong Artificial Intelligence is in charge. And "humans are merely tools for creating the Internet-of-All-Things," says Harai.

Silicon Valley and the Great God Google

Here, in the final third of the book, is where he started to lose me, and not just because he does the classic Silicon Valley outsider thing of misunderstanding Silicon Valley's devotion to data as religious fanaticism.

It's also a very depressing world he's proposing; one in which we 'fess up to the fact that we never had free will in the first place, so we might as well serve the Great God Google. We're all made of information, so let's merge our information and subsume ourselves. If there's anything in the world that can't be reduced to data, ignore it.

Harai regularly concedes there are other possible futures. So his focus on these two — where we become gods and where we serve new gods — seems a bit forced. And that's understandable: any author who blew your mind with something like Sapiens would feel under pressure to deliver an equally wild vision of the future.

Still, it's best considered as two stark warnings for the price of one. No matter what powers technology gives us in the future, let's not worship data at the expense of human instinct. And let us have the courage to embrace our unhappiness, our imperfect minds and failing bodies. Man the wise would be really wise to steer clear of godhood.

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